A new Cardiodectes Wilson, 1917 (Hexanauplia: Copepoda: Siphonostomatoida) parasitic on a scarid teleost (Perciformes: Scaridae) from Roatan Island, Central America.

Members of the parasitic copepod family Pennellidae are highly transformed ecto- or mesoparasites infecting a wide array of marine teleosts. Currently, this family contains more than 20 valid genera. The pennellid genus Cardiodectes Wilson, 1917 is currently known to contain 15 nominal species. Some pennellids exhibit a complex life cycle involving an intermediate host; it is known that planktonic pteropod molluscs are intermediate hosts for Cardiodectes. Pennellid mesoparasites can be detected by the conspicuous female egg-carrying trunk on the host external surface. The copepod cephalothorax is deeply embedded in the host muscle tissue. Members of Cardiodectes have been reported from several teleost families, mainly Myctophidae and Engraulidae. From the parasitological examination of a juvenile individual of a scarid teleost collected in a reef lagoon of Roatan Island, Honduras, Central America, several ovigerous female individuals of a mesoparasitic pennellid copepod were found; these specimens were recognized as representative of an undescribed species of Cardiodectes Wilson, 1917. The new species, C. roatanensis n. sp., differs from its known congeners in several respects, including the presence of neck lobes, paired posterior protuberances of the trunk, trunk shape and proportions, structure of cephalothorax lobes, cephalothorax relative size, and number of legs. The new species from Roatan is the second member of this copepod genus to be reported from the Caribbean region, after C. boxshalli Bellwood, 1981 from off Jamaica (Bellwood 1981). It is also the second report of Cardiodectes on a parrotfish.

A new Bradophila Marchenkov, 2002 (Copepoda, Cyclopoida, Bradophilidae) parasitic on a flabelligerid polychaete from the Chukchi Sea.

The cyclopoid copepod family Bradophilidae includes a few species of mesoparasitic copepods infecting flabelligerid polychaetes. It contains two species of Bradophila Levinsen, 1878, the type genus: B. pygmaea Levinsen, 1878 and B. minuta Boxshall, O'Reilly, Sikorski & Summerfield, 2019, both known from North Europe. Two other genera (i.e., Trophoniphila M'Intosh, 1885 and Flabellicola Gravier, 1918) have some affinities with this family including their host preference. Mesoparasitic copepods are highly specialized, morphologically reduced forms. Part of their body (endosoma) is partially lodged in the host body and the other part is external (ectosoma); both parts are connected by an intersomital stalk. Infection by these copepods can be readily detected by the presence of the egg-carrying ectosoma on the host external surface. From the analysis of flabelligerid polychaetes collected in 2012 from the Chukchi Sea, two ovigerous female individuals of a bradophilid copepod were recorded. These specimens were recognized as representative of an undescribed species of Bradophila. The new species, B. susanae n. sp., shows the generic diagnostic characters and differs from its two other known congeners in several respects, including the cuticular ectosomal ornamentation, body proportions, size of the intersomital stalk, position of the genital pore, and shape and arrangement of egg sacs. Also, the new species ectosomal size range (0.440 - 0.450 µm) falls between the size range of its two known congeners. Our finding expands the known host range of bradophilid copepods to include a new flabelligerid host, Bradabyssa nuda (Annenkova-Chlopina) from the Russsian Arctic region.

Complementary description of Ergasilus arthrosis Roberts, 1969 (Copepoda: Poecilostomatoida: Ergasilidae), a new parasite of cichlid teleosts in southeast Mexico.

During a parasitological survey of the ichthyofauna of Lake Catemaco, a freshwater system in the Mexican State of Veracruz, the widespread copepod Ergasilus arthrosis Roberts, 1969 was recovered from two cichlid teleosts, Mayaheros urophthalmus (Günther) and Oreochromis sp. This is the first confirmed record of this copepod species outside of the United States and from Mexico; its finding as a parasite of cichlids represents an expansion of the known host range for this copepod. The local prevalence and intensity of infection of E. arthrosis was highest in M. urophthalmus. The infection prevalence of E. arthrosis on M. urophthalmus (60%) was higher than that known for other ergasilids on cichlids. Ergasilus arthrosis can be distinguished from its closest congener E. lizae Krøyer, 1863 by the morphometry of the antennary segments, the ventral ornamentation of the thoracic sclerites and by details of the antennulary setation, but also by its habitat and host preferences. Taxonomic illustrations and morphological details of the specimens examined are also provided together with comments on the variability of this species.

A new species of Ergasilus Nordmann, 1832 (Copepoda: Cyclopoida: Ergasilidae) from Bryconops giacopinii Fernández-Yépez (Characidae) in the Vichada River Basin, Colombia.

A new copepod species, Ergasilus curticrus n. sp. is described based on 14 female specimens collected from the gills of the characid teleost Bryconops giacopinii Fernández-Yépez, captured in the Vichada River Basin in Colombia. The new species has a unique combination of characters including: (i) 2-segmented endopods in legs 1 and 4; (ii) a semi-pinnate, falciform seta on the terminal segment of the first leg exopod; (iii) a 1-segmented fourth leg exopod; (iv) a reduced fifth leg with a single seta; and (v) a circular structure fused to a groove near the lateral margins of the second pedigerous tergite. Only two other known congeners have a 1-segmented leg 4 exopod, E. coatiarus Araujo & Varella, 1998 and E. iheringi Tidd, 1942. Among other characters, they differ from the new species by the lack of a semi-pinnate, falciform seta on the terminal exopodal segment of leg 1 and in the structure and armature of the fifth leg. The prevalence of E. curticrus n. sp. was 13.6% and its mean abundance was 0.4 specimens per host. This is the first new species of Ergasilus Nordmann, 1832 described from the Orinoco River Basin.

Historical biogeography of the neotropical Diaptomidae (Crustacea: Copepoda).

INTRODUCTION: Diaptomid copepods are prevalent throughout continental waters of the Neotropics, yet little is known about their biogeography. In this study we investigate the main biogeographical patterns among the neotropical freshwater diaptomid copepods using Parsimony Analysis of Endemicity (PAE) based on species records within ecoregions. In addition, we assess potential environmental correlates and limits for species richness. RESULTS: PAE was efficient in identifying general areas of endemism. Moreover, only ecoregion area showed a significant correlation with diaptomid species richness, although climatic factors were shown to provide possible upper limits to the species richness in a given ecoregion. CONCLUSION: The main patterns of endemism in neotropical freshwater diaptomid copepods are highly congruent with other freshwater taxa, suggesting a strong historical signal in determining the distribution of the family in the Neotropics.

The Australian Monstrilloida (Crustacea: Copepoda) I. Monstrillopsis Sars, Maemonstrilla Grygier & Ohtsuka, and Australomonstrillopsis gen. nov.

Monstrilloid copepods were collected during zooplankton surveys in reef and coastal areas of Australia. Representatives of all four genera of the Monstrilloida (Monstrilla Dana, Monstrillopsis Sars, Cymbasoma Thompson, and Maemonstrilla Grygier & Ohtsuka) were recorded. In this contribution a taxonomic analysis of specimens belonging to the latter two genera is provided, and a new genus described. The genus Monstrillopsis was represented exclusively by male specimens, on the basis of which three new species are described: Mon. hastata sp. nov., Mon. boonwurrungorum sp. nov., and Mon. nanus sp. nov. These are distinguished from each other and previously described species of this genus by details of the genital complex (or genital apparatus), body size, ornamentation of the cephalic surface, number of caudal setae, and characteristic modifications of the fifth antennular segment. All have distinctive characters not associated with sexual modifications, which will ease the task of matching females collected in future studies. Australomonstrillopsis gen. nov. is proposed to accommodate a male specimen with a unique combination of characters including massively developed caudal rami, cephalic perioral protuberances, and absence of an inner seta on the first exopodal segment of legs 1-4, among other characters. The new genus is monotypic and contains A. crassicaudata sp. nov. Three of the four new species of Maemonstrilla (Mae. ohtsukai sp. nov., Mae. hoi sp. nov., and Mae. protuberans sp. nov.) belong to the Mae. hyottoko species group, and the remaining one, Mae. crenulata sp. nov., belongs to the Mae. turgida group. Each of the new species of Maemonstrilla from Australia can be distinguished from its known congeners by a unique combination of characters including the type of body reticulation, body size, antennule and body proportions, distinctive characters of the swimming legs, details of the antennular armature, and the presence/absence of a posteroventral process on the genital compound somite. With the addition of the four new species of Monstrillopsis and the four of Maemonstrilla described herein, the number of species in these genera has increased to 13 and 11 species, respectively. In no case did congeneric species co-occur, hinting that there may be a rich species diversity yet to be discovered within the Australian Monstrilloida.

Mastigodiaptomus galapagoensis n. sp. (Crustacea: Copepoda: Diaptomidae), a possibly extinct copepod from a crater lake of the Galápagos archipelago.

Background: A new species of a Neotropical diaptomid copepod is described based on individuals recovered from a small, almost forgotten collection of unique plankton samples from El Junco, a crater lake in San Cristóbal island, Galápagos archipelago. This copepod was regularly reported (1966-2004) as an abundant zooplankter in the lake, but it was not found in subsequent plankton surveys (2007-2018), and its specific identity remained unknown. In 2020, it was declared extinct because of introduced fish predation, rotenone treatment, and other major disturbances. The taxonomic examination of these invaluable specimens allowed us to recognize them as representing an undescribed species of the freshwater diaptomid genus Mastigodiaptomus Light, 1939. Methods: Here, we describe the new species from El Junco crater lake, located in the San Cristóbal island a part of the Galápagos archipelago, collected with plankton nets. The description is based on detailed morphology, based on SEM and light microscopy. Results: The taxonomic examination of these invaluable specimens allowed us to recognize them as representing an undescribed species of the freshwater diaptomid genus Mastigodiaptomus Light, 1939. The new species was readily assigned to this genus and is distinguished from its known congeners by details of (1) the male right fifth leg terminal claw and aculeus, (2) spiniform processes pattern of the right geniculate antennule segments 10-16, (3) length and structure of the spiniform process of the antepenultimate segment of the male right antennule, and (4) details of the dorsal process on the female fourth pediger. This finding represents the first report of this Neotropical copepod genus outside its original biogeographic region, the third species of a diaptomid copepod reported from insular freshwater systems, the southernmost record of Mastigodiaptomus, and the only freshwater calanoid in the Galápagos. The intriguing presence of this chiefly Neotropical copepod genus here could be related either to (1) human agency linked to pirate activities, commercial travelling by Spaniard ships, whaling activities, and intense tortoise hunting in San Cristóbal island. In the past, El Junco was the only freshwater source 600 nautical miles around, or (2) zoochory of resistant dormant stages passively transported by more than 65 migrating bird species known to settle in San Cristóbal. These two hypotheses cannot be properly tested at this time, so the explanation of the presence of this copepod will remain as a new open question in the fascinating natural history of the Galápagos.

A new species of the rare endoparasitic copepod Entobius (Copepoda: Entobiidae) from Mexico with a key to the species of the genus.

Abstract: In a study of the benthic polychaete fauna of the southern Gulf of Mexico and the Caribbean Sea, several specimens of the terebellid polychaete Scionides reticulata (Ehlers) were found to host endoparasitic copepods that represent an undescribed species of the rare cyclopoid genus Entobius Dogiel, 1948. The new species, E. scionides sp. n., can be distinguished from its congeners by a combination of characters including a genital region without constrictions, three-segmented antennules, a reduced antenna with a blunt terminal process, reduced ornamentation of endopods of legs 1-4 and its relatively small size (2.3-2.7 mm). It is the smallest species of the genus. Comments on immature females are also provided, but males of this species remain unknown. It has a high prevalence (53%) in populations of the terebellid S. reticulata in the southern Gulf of Mexico, but it is absent from the Caribbean. This is the first occurrence of this copepod genus in the Americas. The finding of the new species of Entobius in S. reticulata confirms the strict specificity of most members of the genus and expands the host range of this copepod genus. A key for the identification of the species of Entobius is provided.

A new species of Sabellacheres M. Sars, 1862 (Copepoda: Gastrodelphyidae) from a deep-water benthic polychaete in Antarctic waters, with a key to the species of the genus.

Specimens of a deep-living sabellid polychaete of the genus Perkinsiana Knight-Jones dredged in Antarctic waters were found to be parasitised by an undescribed species of the cyclopoid copepod genus Sabellacheres M. Sars, 1862. Specimens of both sexes were studied using light microscopy and SEM, and compared with its congeners. The new species, Sabellacheres antarcticus n. sp., can be distinguished from its congeners by the shape and proportions of the body and brood-pouch, its 4-segmented antennae, the shape and length of the distal process of the second antennular segment, the position of leg 3, and the structure of the male maxilliped. This is only the second record of a species of this genus from the southern hemisphere. The new species was found on a single host species, as is typical for most species of Sabellacheres. A key for the identification of both sexes of the species of Sabellacheres is included.

A new species of Monstrilla (Copepoda, Monstrilloida) from the western Caribbean with comments on M.wandelii Stephensen, 1913 and M.conjunctiva Giesbrecht, 1893.

The taxonomic study of monstrilloid copepods is hampered by incomplete early descriptions, uncertain synonymies, and the difficulty of reliably matching males and females of species. A re-evaluation of male monstrilloid specimens collected from two reef areas of the Mexican Caribbean allowed me to clarify the status of Monstrillamariaeugeniae Suárez-Morales & Islas-Landeros, 1993 and M.wandelii Stephensen, 1913 based on a comparison of males attributed to each of these species. Males from the Puerto Morelos reef system, northern Mexican Caribbean coast, were first proposed as a tropical subspecies of the subarctic M.wandelii; later on, morphologically close males collected from the Mahahual reef area, southern Mexican Caribbean coast, were designated as the males of M.mariaeugeniae. Their status is here corrected with the description of M.mahahualensis sp. nov. based on the Mahahual males; the new species shares the same type of genitalia with the antarctic M.conjunctiva Giesbrecht, 1892 and the subarctic M.wandelii; Park (1967) linked a single male from Vancouver to M.wandelii. It was realised that Park's (1967) males from the Vancouver area and the two Mexican Caribbean groups of males represent different, undescribed species. I here reassign the males earlier attributed to M.mariaeugeniae as a new species of Monstrilla which is herein described. The new species differs from the males of M.conjunctiva and M.wandelii by details of the genitalia, length of the setae of the fifth legs, armature and integumental structures of the antennules, and size of the outer exopodal spines of legs 1-4. This is the third known species of Monstrilla with a M.conjunctiva-like male genitalia and the first one known from tropical areas. The male of both M.mariaeugeniae and M.wandelii remain unknown.

A new species of Nitokra Boeck, 1865 (Copepoda, Harpacticoida, Ameiridae) from the Caribbean coast of Colombia.

Biological samples obtained from a coastal system of northern Colombia yielded male and female specimens of an undescribed harpacticoid copepod of the diverse ameirid genus Nitokra Boeck, 1865. The new species is a member of the genus group III. We describe the new species based on adult male and female individuals. Nitokrapuebloviejensis sp. nov., appears to be most closely related to N.vietnamensis Tran & Chang, 2012, but they can be separated by the following characters: 1) number of setal elements on second segment of mandibular palp, 2) P1ENP/EXP ratio, 3) relative lengths of P2, P3ENP/EXP, 4) number of elements on male P5EXP and ENP, and 5) segmentation of male antennule. In addition, N.puebloviejensis sp. nov. can be confused with two other congeners: N.taylori Gómez, Carrasco & Morales-Serna, 2012 from South Africa and Colombia and N.kastjanensis Kornev & Chertoprud, 2008 from the White Sea, but the new species can be distinguished from them by: 1) number of setae on the maxillule coxa, 2) P1ENP/EXP ratio, 3) P2,P3ENP/EXP ratio, 4) female and male P5 setophore, 5) setation pattern of female P5EXP and ENP, 6) structure of female P6, 7) ornamentation of female anal operculum, 8) number of setae on male P5EXP, and 9) the male antennule segmentation. Most importantly, the presence of a group of five short setae on the medial surface of the maxilliped syncoxa allows the new species to be readily distinguished from its congeners. Only two subspecies and one species of this genus have been hitherto recorded from Colombia. A key to the 23 known American species of Nitokra is provided.

A new species of Esola Edwards, 1891 (Crustacea, Copepoda, Harpacticoida, Laophontidae) from the Caribbean coast of Colombia.

A new species of the harpacticoid copepod genus Esola is described from specimens collected in Rodadero Beach, on Gaira Bay, on the Caribbean coast of Colombia. The species, E.wellsi sp. nov., is described, illustrated, and com-pared with its congeners. Esolawellsi sp. nov. differs from its known congeners in details of the armature of legs 1-4. It most closely resembles E.bulbifera (Norman, 1911) in the armature formula of P1-P5 but differs from the latter in several respects, including the female antennule segmentation (7-segmented in E.bulbifera but distinctly 6-segmented in E.wellsi sp. nov.) and in the shape and size of the male P3ENP2 apophysis, among other characters. This is the second species of the genus known from the Caribbean and the second record of Esola in the Northwestern Tropical Atlantic. The genus now contains eight species. A key to the known species of the genus is also included.

The introduced Asian parasitic copepod Neoergasilus japonicus (Harada) (Cyclopoida: Ergasilidae) from endangered cichlid teleosts in Mexico.

The cyclopoid copepod Neoergasilus japonicus ( Harada, 1930 ) is recorded from three endangered or threatened fish species from southeast Mexico: the tailbar cichlid Vieja hartwegi (Taylor and Miller, 1980); the Angostura cichlid V. breidohri (Werner and Stawikowski, 1987); and the sieve cichlid C. grammodes (Taylor and Miller, 1980). This ectoparasitic copepod is considered, together with most other members of Neoergasilus, an Eastern Asian form. N. japonicus is one of the most widespread parasitic Asian copepods, as it has rapidly invaded Europe and North America, including Mexico. We estimated the prevalence, mean abundance, and intensity of infection of N. japonicus in these cichlid teleosts; our data agree with previous works stating the high prevalence of this ectoparasite. This copepod has a wide range of hosts among freshwater fish taxa, but this is only the second published report from cichlids in the Neotropical region. The three cichlids surveyed, V. hartwegi, V. breidohri, and C. grammodes, are new hosts of this copepod. Its occurrence in Mexico is attributed to different events of introduction by human agency. This is the southernmost record of N. japonicus in continental America. It is a matter of concern that this copepod is parasitizing endangered or threatened endemic cichlids in the Neotropical region. Because its high infective efficiency and ability to shift hosts, this Asian parasite is expected to spread farther southwards into Central and South America.

Validation of Cymbasoma turcorum and Monstrillopsis pontoeuxinensis, two monstrilloids from Turkey described by Suárez-Morales amp; Üstün in 2018 (Crustacea: Copepoda: Monstrilloida).

Recently, Suárez-Morales Üstün (2018) described two new species of monstrilloid copepods, Cymbasoma turcorum and Monstrillopsis pontoeuxinensis from Turkish coastal waters of the Black Sea. The morphological descriptions, illustrations, and type designations presented in that paper fully characterized both new species; however, the journal issue in which the description appeared was published only online, with no print version (Suárez-Morales Üstün 2018), and the article in which these new names were introduced did not include a ZooBank registration number (LSID) for the article or any other evidence of such registration. This is currently required by Article 8.5 of the International Code of Zoological Nomenclature for an electronic work to be deemed "published" under the Code (International Commission on Zoological Nomenclature 2012). Inasmuch as Suárez-Morales Üstün (2018) is an "unpublished work", the specific names turcorum and pontoeuxinensis proposed in it are unavailable. The present note is intended to fully validate these two names by proposing them once again as new while also fulfilling all of the Code's current conditions for nomenclatural availability of this work itself and the two new names. The date and authorship of these two specific names will, accordingly, be those of this note, not Suárez-Morales Üstün (2018).

Discovery of the fish host of the 'planktonic' caligid Caligus undulatus Shen & Li, 1959 (Crustacea: Copepoda: Siphonostomatoida).

The siphonostomatoid copepod Caligus undulatus Shen & Li, 1959 has been widely reported from plankton samples obtained from neritic and oceanic waters off coasts of the Indo-West Pacific and Atlantic Oceans. Until now, its fish host has remained unknown. This copepod belongs to an intriguing group of congeners that, despite being part of a chiefly parasitic group, are consistently found as zooplankters. Quite unexpectedly, in October 2019, a fish host of C. undulatus was discovered in the Seto Inland Sea, Japan-namely, the Japanese sardinella Sardinella zunasi (Bleeker, 1854). Both juvenile (chalimus) and adult individuals of this caligid were observed as parasites of the fish host. The discovery suggests that the species has an alternative life cycle as previously proposed for other purportedly 'planktonic' congeners and might frequently switch hosts during the adult stage. Thus, the C. undulatus group is newly proposed as a species group in the genus, in which five species are known as planktonic. Some hypotheses on the modified life cycle of caligids also briefly discussed.

The 2015-2016 El Niño increased infection parameters of copepods on Eastern Tropical Pacific dolphinfish populations.

The oceanographic conditions of the Pacific Ocean are largely modified by El Niño (EN), affecting several ecological processes. Parasites and other marine organisms respond to environmental variation, but the influence of the EN cycle on the seasonal variation of parasitic copepods has not been yet evaluated. We analysed the relation between infection parameters (prevalence and mean intensity) of the widespread parasitic copepods Caligus bonito and Charopinopsis quaternia in the dolphinfish Coryphaena hippurus and oceanography during the strong 2015-16 EN. Fish were collected from capture fisheries on the Ecuadorian coast (Tropical Eastern Pacific) over a 2-year period. Variations of sea surface temperature (SST), salinity, chlorophyll a (Chl-a), Oceanic Niño Index (ONI), total host length (TL) and monthly infection parameters of both copepod species were analysed using time series and cross-correlations. We used the generalised additive models for determine the relationship between environmental variables and infection parameters. The total body length of the ovigerous females and the length of the eggs of C. bonito were measured in both periods. Infection parameters of both C. bonito and Ch. quaternia showed seasonal and annual patterns associated with the variation of environmental variables examined (SST, salinity, Chl-a and ONI 1+2). Infection parameters of both copepod species were significantly correlated with ONI 1+2, SST, TL and Chl-a throughout the GAMLSS model, and the explained deviance contribution ranged from 16%-36%. Our results suggest than an anomaly higher than +0.5°C triggers a risen in infection parameters of both parasitic copepods. This risen could be related to increases in egg length, female numbers and the total length of the ovigerous females in EN period. This study provides the first evidence showing that tropical parasitic copepods are sensitive to the influence of EN event, especially from SST variations. The observed behaviour of parasitic copepods likely affects the host populations and structure of the marine ecosystem at different scales.

A new species of Monstrilla (Copepoda, Monstrilloida) from the plankton of a large coastal system of the northwestern Caribbean with a key to species.

The genus Monstrilla Dana, 1849 is the most diverse of the copepod order Monstrilloida. Monstrilloid copepods are endoparasites of benthic polychaetes and molluscs; adult individuals are free-living, non-feeding reproductive forms that briefly become part of the zooplankton community, where they are occasionally captured by plankton nets. Monstrilloid copepods are frequently found during routine plankton samplings of coastal and estuarine habitats, but they are rarely found in large numbers. The western sector of the Caribbean Sea is known to harbor a diverse monstrilloid fauna. The analysis of zooplankton samples obtained during nine years from Chetumal Bay, a large embayment of the Mexican Caribbean coast, yielded a male monstrilloid that was found to represent a new species. It is herein described following upgraded standards and compared with its congeners. A key to males and females of the Monstrilla species known from the northwestern Caribbean is also provided.

A new species of Ergasilus (Copepoda:Cyclopoida:Ergasilidae) from coastal fishes of the Mexican Pacific.

A new species of the cyclopoid copepod genus Ergasilus von Nordmann, 1832 is described based on adult female specimens removed from the gills of the yellow snapper Lutjanus argentiventris (Peters) and the yellowfin snook Centropomus robalito Jordan et Gilbert from a Pacific coastal system of Mexico. The new species Ergasilus davidi sp. n. has a combination of characters that includes a two-segmented first leg endopod, a three-segmented fourth leg endopod, and the presence of a single seta on the first antennular segment. These characters are shared with 14 other congeners known mainly from Brazil and North America. It differs from these other species in the armature and ornamentation of legs 1 and 4, the shape of the body, and the structure and ornamentation of the antennae. Additional characters include a maxillar basis armed with blunt teeth, distally bent maxillular setae, and naked margins of first exopodal segments of legs 2-4. Previous regional records of Ergasilus sp. from both fish species are probably assignable to E. davidi. The prevalence and intensity of infection was estimated for both teleost species and agrees to previous data. Based on other records of the genus from several other teleost species in the surveyed area and adjacent zones of the Eastern Pacific, it is presumed that the new species could have a wider range of hosts. The new species represents the first Ergasilus described from Mexican waters of the Pacific. Overall, the genus remains poorly known in Central America and Mexico.

Recognition and partial solution of nomenclatural issues involving copepods of the family Monstrillidae (Crustacea: Copepoda: Monstrilloida).

This work seeks to expose and clear up nomenclatural irregularities involving copepods of the order Monstrilloida, family Monstrillidae. The diagnostic text related to Monstrilla minuta Isaac, 1974 and four nominal species of Thaumaleus Krøyer, 1849 (now Cymbasoma Thompson, 1888) proposed by Isaac in 1974 is sufficient for all names to be available from their original description except for Thaumaleus similirostratus, which was proposed conditionally in 1974 and was first made available by Isaac in 1975; "similirostris" as used by Grygier in 1995 is an incorrect subsequent spelling. Four other specific names proposed in 1975 by Isaac, but disclaimed by him as nomina nuda (an action permitted retroactively by the Fourth Edition of the International Code of Zoological Nomenclature) have never been made available. By quoting the necessary information from Isaac's doctoral dissertation, two of them are validated herein under the names Thaumaleus frondipes Isaac in Grygier Suárez-Morales, sp. nov., and Strilloma scotti Isaac in Grygier Suárez-Morales, sp. nov., and are immediately reassigned as new combinations to Cymbasoma and Monstrilla Dana, 1849, respectively. A fifth such name, Thaumaleus tumorifrons, has already been made available under the authorship of Suárez-Morales, 1999, but its females are excluded from the type series; the spelling of the specific name of the new species recently proposed for those females, Cymbasoma mediterranea Suárez-Morales, Goruppi, Olazabal Tirelli, 2017, is emended to mediterraneum to match the gender of the genus. For Cymbasoma bowmani Suárez-Morales Gasca, 1998, the "Form B" female mentioned in the original description is excluded from the type series. The authorship and date of availability of Haemocera (currently Cymbasoma) morii depends on which language version of Article 13.1.1 of the Code is followed; a ruling by the International Commission on Zoological Nomenclature under Article 87 of the Code is necessary to resolve the matter. The composition of the type series of Cymbasoma bullatum (Scott, 1909) in terms of both number and sex has become unclear; its type locality is restricted herein to the vicinity of Obi Island in the Moluccas. Despite a published statement to the contrary, the syntype series of Cymbasoma germanicum (Timm, 1893) included specimens from other localities than just Helgoland. The type series of Cymbasoma guerrerense Suárez-Morales Morales-Ramírez, 2009 consists only of the holotype, which was mistakenly reported under the wrong registration number. The supposed invalidity of Monstrilla capitellicola Hartman, 1961 is discussed. Monstrilla javensis Isaac, 1974, nomen nudum, has remained unavailable owing to lack of adherence to Article 16.1 of the Code by later authors; the specific name is made available herein, under Suárez-Morales' authorship, in the combination Cymbasoma javense sp. nov. The taxonomic (and eventual nomenclatural) question of the status of M. mariaeugeniae Suárez-Morales Islas-Landeros, 1993 vis à vis M. wandelii Stephensen, 1913, i.e. as a separate species or a subspecies of the latter, remains unsettled. Cymbasoma lenticula Suárez-Morales McKinnon, 2014 and Monstrillopsis boonwurrungorum Suárez-Morales McKinnon, 2014 are fixed herein as the correct original spellings of those two specific names. Resolution of the problem posed by assignment of the specific name reticulata to supposedly non-conspecific males and females in the genus Monstrillopsis Sars, 1921 requires the designation of a neotype by the International Commission on Zoological Nomenclature.

A new species of Pupulina van Beneden, 1892 (Copepoda, Siphonostomatoida, Caligidae) from Aetobatuscf.narinari (Pisces, Myliobatidae) from the Pacific coast of Ecuador.

A new caligid copepod species, Pupulinamantensissp. n. is described based on female and male specimens collected from the gills of the myliobatid elasmobranch Aetobatuscf.narinari Euphrasen, 1790 captured off the Pacific coast of Ecuador. The new species has a unique combination of characters that diverges from its known congeners, including: (i) weakly developed posterolateral processes on the genital complex; (ii) large spines on posterior surface of maxilliped basis (iii) abdomen slender, unsegmented, approximately 1/2 length and 1/5 width of genital complex; (iv) third exopodal segment of leg II with single long naked spine adjacent to minute, naked lateral spine; (v) velum of leg II with adjacent patch of denticles; (vi) caudal rami slightly less than half the length of genital complex; (vii) post-antennal process with robust, posteriorly directed tine, sclerotized stump posterolaterally, and two multi-sensillate papillae located on or near base of process (viii) post-oral process oval. The overall prevalence of P.mantensissp. n. on its host was 37.5% and its mean abundance was 1.87 specimens per host. This is the second record of the genus Pupulina from Ecuador and the second record of Pupulina infecting rays of the Myliobatinae genus Aetobatus, of the subfamily Myliobatinae, after its discovery on A.ocellatus in Australia, thus confirming this expansion of its previously known host range to a new elasmobranch subfamily.